Update on progress in adaptive wind tunnel wall technology

Meyer, Oliver; Nitsche, W.

doi:10.1016/j.paerosci.2004.02.001

Cited by 16 publications

(6 citation statements)

References 15 publications

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“…This was a very stiff model which spanned the width of the test section, and the adaptive top and bottom walls were moved to minimise wall interference at each angle of attack for static airfoil positions. The wall interference velocities were minimised using the Cauchy method of Amecke (1985) (see also the overview by Meyer and Nitsche 2004), which uses a row of measured pressures on the adaptive walls as an input. The model was mounted horizontally in the test section and was driven from drive shafts through the sidewalls attached at the quarter-chord position.…”

Section: Methodsmentioning

confidence: 99%

Boundary layer transition determination for periodic and static flows using phase-averaged pressure data

Gardner

Richter

2015

Exp Fluids

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the power required. Additionally the transition affects the resistance of components to boundary layer separation.As seen in Fig. 1 on the example of a flat plate, the boundary layer is characterised by a laminar part near the leading edge which has low turbulence and wall shear stress. At some point, turbulence in the boundary layer is no longer damped, and the turbulence increases along a "transition region" until the boundary layer is fully turbulent. Compared to the laminar region, the turbulent region has higher recovery temperature, wall heat flux, wall shear stress, and higher RMS values of wall static pressure, Pitot pressure and heat flux (Schlichting and Gersten 2006). These characteristics can be used to detect transition, and the detection of boundary layer transition can be performed by a large number of methods (Nitsche and Brunn 2006), most of which work for transition positions which are invariant with time or quasi-steady with regard to the surface temperature distribution, for example: --Skin friction measurements by piezoelectric sensors (Nitsche and Brunn 2006) or oil films for steady flows (Tanner and Blows 1976) or unsteady flows (Schülein 2014). --Measurements of the transition position by sublimation (Velkoff et al. 1971) or China-clay (Richards and Burstall 1945). --Measurements of the wall recovery temperature by thermocouples, temperature-sensitive paint, temperaturesensitive liquid crystals or infrared cameras (Peake et al. 1977). --Measurements of the wall heat transfer by thermocouples, infrared cameras, or direct measurements by hotfilm anemometers (Schultz and Jones 1973). --Measurements of the boundary layer velocity profile by hot-wire anemometers, Pitot tube or PIV (Nitsche and Brunn 2006).Abstract A method of boundary layer transition measurement is presented for wind tunnel models instrumented with surface pressure taps. The measurement relies on taking a number of theoretically identical measurements at different times and then analysing the standard deviation of the pressures. Due to the slight unsteady movement of the transition position, a peak in the standard deviation of pressure σ C P peak is found at the transition position, and this is correlated with measurements of the transition position with an infrared camera and hot-film anemometers. In contrast to microphone measurements, it is shown that the transition detection works for data which have been low-pass filtered with a cut-off of 1 Hz. The application to static and dynamic transition measurements on static and periodically pitching helicopter rotor blade airfoils at Mach 0.3-0.5 is demonstrated.

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Section: Methodsmentioning

confidence: 99%

Boundary layer transition determination for periodic and static flows using phase-averaged pressure data

Gardner

Richter

2015

Exp Fluids

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“…Increasing the size of the model without giving a thought about blockage effects can lead to chocking of the flow in the test section and improper shock wave pattern on the airfoil surface. Wind tunnels with adaptive wall test sections, ventilated test sections or slotted/perforated wall test sections are used to overcome these problems [2]. Adaptive wall test sections have flexible liners and actuators to change the wall geometry to relieve the flow around the model.…”

Section: Introductionmentioning

confidence: 99%

Characterization of RAE 2822 Transonic Airfoil in FSU Polysonic Wind Tunnel Facility

Ramasamy¹,

Richardson²,

Gustavsson³

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Wind tunnel tests were carried out to characterize the RAE 2822 supercritical airfoil and implement an active flow control technique. Tests were carried out at various subsonic and transonic Mach numbers and angles of attack. Two load cells connected to the airfoil ends along the quarter chord axis were used to quantify the aerodynamic forces acting on the airfoil. The transonic airfoil was integrated, and the control technique successfully implemented at the Florida State University Polysonic wind tunnel. The paper presents a few preliminary experimental results and describes the lessons learned during the implementation process. Oil flow visualizations revealed the presence of corner vortices on the airfoil suction surface and wedge-like patterns on the lower surface, which indicates a combination of localized regions of transitional and turbulent flow with no shocks or very weak shocks. The measured lift coefficient on the baseline airfoil is much lower than the estimated value based on literature. These results indicate that the airfoil tested need to be modified both regarding its aspect ratio and cross-sectional area to suit the facility. The active flow control technique based on co-flow jet show promise in the improvement of aerodynamic performance.

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“…An important task of this measurement campaign was to assess the effects of slotted and closed walls within the test section. While slotted walls offer advantages regarding the wind tunnel's aerodynamic performance [20], the aeroacoustic disturbance induced by the flow through the slots is rather unknown. Figure 11 shows that the auto power of the microphones is increased, but so is the reconstructed sound emission below St < 60.…”

Section: Slotted and Closed Test Sectionmentioning

confidence: 99%

“…By varying temperature and static pressure three different Mach numbers in the range from 0.220 to 0.289 are observed at the constant Reynolds number 10 7 . Further, the influence of closed and slotted test sections is examined, as slotted test sections offer aerodynamic advantages [20], but their potential aeroacoustic effects on the model or the array are unknown. Section 3 presents the necessary tools for the correction and evaluation of the measurements.…”

Section: Introductionmentioning

confidence: 99%

Aeroacoustic testing on a full aircraft model at high Reynolds numbers in the European Transonic Windtunnel

Ahlefeldt

Ernst

Goudarzi

et al. 2023

Journal of Sound and Vibration

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Update on progress in adaptive wind tunnel wall technology

Cited by 16 publications

References 15 publications

Boundary layer transition determination for periodic and static flows using phase-averaged pressure data

Boundary layer transition determination for periodic and static flows using phase-averaged pressure data

Characterization of RAE 2822 Transonic Airfoil in FSU Polysonic Wind Tunnel Facility

Aeroacoustic testing on a full aircraft model at high Reynolds numbers in the European Transonic Windtunnel

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